In my Australian Pat. No. 531,374 and my corresponding U.S. Pat. No. 4,441,534 I disclosed apparatus for cutting or grinding tree stumps which is driven by a chain saw drive motor and which includes a multi-toothed cutting disc for cutting or grinding tree stumps. Preferably and in order to achieve a wider cut, the cutting disc is supported at an inclined angle relative to the shaft so that it undergoes oscillation in use. This arrangement, while being relatively effective, results in wastage of power from the drive motor. Another disadvantage of such arrangements is that the tungsten tipped tooth portions of the cutting disc tend to be frequently broken or damaged in use, necessitating repair which results in downtime of machine and/or high costs.